Magento Adminpanel - Custom Grid Error on Filter

Question

I have created a custom Grid in the adminpanel where i need to show orders and the last comment for the order. I did this by adding Join in the _prepareCollection function and the data is showing properly.

protected function _prepareCollection()
    {
        $collection = Mage::getResourceModel($this->_getCollectionClass());
        $subquery = new Zend_Db_Expr('(SELECT parent_id,MAX(entity_id) as comment_id,created_at as comment_date,comment FROM sales_flat_order_status_history GROUP BY parent_id ORDER BY `sales_flat_order_status_history`.`parent_id` DESC)');
        $collection->getSelect()->joinLeft(array('c'=>$subquery), 'c.parent_id = main_table.entity_id', array('c.*'));
        //echo $collection->getSelect();exit;
        $this->setCollection($collection);
        return parent::_prepareCollection();
    }

However if i try to filter the comment column its showing following error.

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'comment' in 'where clause'

What i'm missing. Please help me to resolve this.

Answer 1

Found a solution for the issue. We need to call custom function for filter for custom columns This is done by as follows.

$this->addColumn('comment', array(
            'header' => Mage::helper('sales')->__('Comment'),
            'index' => 'comment',
            'filter_condition_callback' => array($this,'filterComment'),
        ));

public function filterComment($collection, $column) {

        if (!$value = $column->getFilter()->getValue()) {
            return $this;
        }
        $collection->getSelect()->where(
        "c.comment like ?", "%$value%");
        return $this;
    }